The Extensible Stylesheet Language and XPath Language
The Extensible Stylesheet Language, also referred to as XSL is a programming language designed to create style sheets for that describes how data, transmitted over the web using Extensible Markup Language, will be presented. Similarly, XPath is a language created for describing a way for locating and processing items in Extensible Markup Language (XML) documents.
One of the examples for XSL language is an XML page describing the features of vehicles for an insurance company. A group of open/close tags could have the name of the car manufacturer. XSL makes it possible for the user to inform the browser about the name of the car manufacturer be displayed. It is also possible to control where the name is to be displayed on the page and in which font.
An XML page is just like an HTML page, but it has data in well-defined fields as compared to textual and graphical content. XSL provides a developer all of the tools required for describing the data fields in the XML file to be displayed. It is also possible to determine how and where to display the fields. Similar to other style sheet languages, XSL could also be used for creating style definition for a single XML document or it could be used again for several XML documents.
XPath is a language developed for describing the way for locating and processing items in XML documents. This is achieved through the use of an addressing syntax. This syntax is based on the logical structure of the document. It is possible to write easier programming expressions as compared to having each expression understand the XML markup and the sequence within the document.
The XPath Language also enables programmers to handle the documents at a higher level. This language is typically considered to be part of both XPointer and Extensible Stylesheet Language Transformations. It is based on the information abstraction found in the XML Information Set. One of the advantages of this language is that it could be used in contexts beyond the XML. This is because it doesn’t rely on XML syntax.